Fix a large number of typos and other problems (#110)

Most of these fixes are for typos and extra whitespace at the
end of lines. These are the notable changes:
- Fixed a compatibility issue with how asterisks are displayed
  using certain fonts. Bug report: https://github.com/att/ast/issues/764
- Fixed a bug in the man page that caused searches for the '|'
  character to fail. Bug report: https://github.com/att/ast/issues/871
- Removed a duplicate description of 'set -B' from the man
  page. Bug report: https://github.com/att/ast/issues/789
- Added documentation for options missing from the ksh man
  page (applies to 'hist -N', 'sleep -s', 'whence -q' and
  many of ulimit's options). Bug reports:
  https://github.com/att/ast/issues/948
  https://github.com/att/ast/issues/503#issuecomment-386649715
  https://github.com/att/ast/issues/507#issuecomment-507924608
- Applied the following ksh2020 documentation fixes:
  https://github.com/att/ast/pull/351
  https://github.com/att/ast/pull/352
- Fixed a minor GCC -Wformat warning in procopen.c by changing
  a sentinel to NULL.

src/lib/libast/comp/omitted.c

@@ -529,7 +529,7 @@ runve(int mode, const char* path, char* const* argv, char* const* envv)
 	 *	(3) /c/(WINNT|WINDOWS)/system32 /c/(WINNT|WINDOWS)
 	 *	(4) the directories on $PATH
 	 * there are no cygwin dlls in (3), so if (1) and (2) fail
-	 * to produce the required dlls its up to (4)
+	 * to produce the required dlls it's up to (4)
 	 *
 	 * the standard allows PATH to be anything once the path
 	 * to an executable is determined; this code ensures that PATH